Linear actuator with releasably interlocking bands

Abstract

The linear actuator comprises an elongated first band wound in helical form about a central axis and capable of taking a retracted position and an extended position with its turns spaced from one another in the direction of the central axis, and first fasteners carried by the first band and longitudinally disposed therealong. The linear actuator also comprises an elongated second substantially flat band wound on itself, with its turns substantially transversely parallel to the central axis, and capable of taking a retracted, spiral position with its turns nested within one another and an extended position with its turns forming a helix around the central axis and generally equally radially spaced therefrom to form a telescopic column, the first and second bands, when in retracted position, in respective locations so as to clear each other. Second fasteners are carried by the second band and longitudinally disposed therealong, the second fasteners capable of cooperating with the first fasteners to releasably interlock the first and second bands. A spacer successively spaces the turns of the first band. A powered drive causes relative rotation on one hand of the first and second bands and on the other hand of the spacer about the central axis. Guide means guide the turns of the second band towards the turns of the first band to releasably interlock the first and second fasteners. A retaining member retains the first and second fasteners in interlocked fashion in the telescopic column.

1. A linear actuator comprising:
 an elongated first band wound in helical form about a central axis and capable of taking a retracted position and an extended position with its turns spaced from one another in the direction of said central axis; 
 first fastening means carried by said first band and longitudinally disposed therealong; 
 an elongated second substantially flat band wound on itself, with its turns substantially transversely parallel to said central axis, and capable of taking a retracted, spiral position with its turns nested within one another and an extended position with its turns forming a helix around said central axis and generally equally radially spaced therefrom to form a telescopic column, said first and second bands, when in retracted position, in respective locations so as to clear each other; 
 second fastening means carried by said second band and longitudinally disposed therealong, said second fastening means capable of cooperating with said first fastening means to releasably interlock said first and second bands; 
 spacer means to successively space the turns of said first band; 
 drive means to cause relative rotation on one hand of said first and second bands and on the other hand of said spacer means about said central axis; 
 guide means to guide the turns of said second band towards the turns of said first band to releasably interlock said first and second fastening means; and 
 retaining means retaining said first and second fastening means in interlocked fashion in said telescopic column. 
 
   
   
     2. A linear actuator as defined in  claim 1 , wherein each said two consecutive turns of said second band that form said retractable telescopic column partly overlap to form an overlapping section, with a portion of said first band being wound in a helix adjacent to said overlapping section and with said first and second fastening means engaging each other at said overlapping section to releasably link said each two consecutive turns of said second band that form said retractable telescopic column. 
   
   
     3. A linear actuator as defined in  claim 2 , wherein said first fastening means comprise longitudinally spaced-apart teeth protruding from said first band, and said second fastening means comprise openings longitudinally disposed along said second band and positioned in said each two consecutive turns of said second band that form said retractable telescopic column so as to register in said overlapping section by pairs, with at least some of said pairs of openings being engaged by corresponding said teeth. 
   
   
     4. A linear actuator as defined in  claim 3 , wherein said retaining member and said guiding member are a roller mounted to said rotor. 
   
   
     5. A linear actuator as defined in  claim 2 , wherein said second band is preformed in an inclined configuration so that each turn defines a slightly conical shape. 
   
   
     6. A linear actuator as defined in  claim 1 , further comprising a first anti-rotation member attached to either one of said structural and first bands and engaging a second anti-rotation member attached to said frame, wherein said structural and first bands are prevented from rotating. 
   
   
     7. A linear actuator as defined in  claim 3 , wherein said teeth are also first anti-rotation members that cooperate with second anti-rotation members provided on said frame in spaced-apart fashion around said central axis, with at least one of said teeth engaging a corresponding space defined between two said second anti-rotation members at all times, wherein said structural and first bands are prevented from rotating while they are moved between their extended and retracted positions. 
   
   
     8. A linear actuator as defined in  claim 1 , wherein said drive means includes a power driven rotor rotatably mounted to a first frame portion, said rotor carrying said guide means, said retaining means and said spacer means, said linear actuator also comprising a second band magazine movable relative to said rotor and said frame and carrying the portion of said second band which is in said retracted, spiral position with its turns nested within one another, said first and second elongated bands having a first end located near said first frame portion and a second end attached to a second frame portion. 
   
   
     9. A linear actuator as defined in  claim 8 , wherein said spacer means includes a support member having a helical configuration, carried by said rotor and engaged by a portion of said first band. 
   
   
     10. A linear actuator as defined in  claim 9 , wherein said support member is a helical groove. 
   
   
     11. A linear actuator as defined in  claim 1 , further comprising:
 a first frame portion carrying said spacer means, said guide means, said retaining means and a second band magazine movable relative to said first frame portion and carrying the portion of said second band which is in said retracted, spiral position with its turns nested within one another; and 
 a second frame portion, with said drive means including a power driven rotor fixedly attached to a first end of said first and second bands and rotatably carried by said second frame portion. 
 
   
   
     12. A linear actuator as defined in  claim 11 , wherein said spacer means includes a support member having a helical configuration, carried by said first frame portion and engaged by a portion of said first band. 
   
   
     13. A linear actuator as defined in  claim 9 , wherein said support member is a helical groove made in said first frame portion. 
   
   
     14. An elongated linear actuator having opposite first and second ends and an intermediate portion between said first and second ends, said linear actuator further defining a central axis extending between said first and second ends and comprising:
 a frame comprising a first frame portion at said first end and a second frame portion at said second end movable relative to said first frame portion between retracted and extracted positions, with said second frame portion being closer to said first frame portion in said retracted position than in said extracted position; 
 a rotor member rotatably carried by said first frame portion and rotatable about said central axis; 
 drive means, capable of selectively rotating said rotor member relative to said first frame portion; 
 a first elongated band wound according to a helical pattern about said central axis, having a first end portion adjacent to said linear actuator first end and a second end portion attached to said second frame portion, and comprising longitudinally disposed releasable fasteners; 
 a second elongated substantially flat band substantially parallel to said central axis and wound about said central axis in a helical configuration between said intermediate portion and said second end and in a spiral configuration between said intermediate portion and said first end, said second band having a first end portion adjacent to said linear actuator first end and a second end portion attached to said second frame portion; 
 a support member carried by said rotor in a helical pattern about said central axis, with part of said first band movably engaging said support member and allowing rotation of said rotor member relative to said first band; 
 a guiding member at said linear actuator intermediate portion and carried by said rotor member, said guiding member guiding said second band in a transition between its said spiral and helical configurations, said guiding member guiding each turn of said second band substantially edgewisely adjacent to the preceding turn of said second band between said intermediate portion and said second end when said rotor member is rotated in a first direction around said central axis, with said fasteners of said first band engaging and releasably linking each two consecutive turns of said second band between said intermediate portion and said second end thus forming a retractable telescopic column composed of the releasably interconnected first and second bands between said intermediate portion and said second end, with said first and said second bands each being independently stackable between said intermediate portion and said first end; and 
 a retaining member retaining said first and second bands in their releasably interconnected relationship between said intermediate portion and said second end. 
 
   
   
     15. A linear actuator as defined in  claim 14 , wherein each said two consecutive turns of said second band that form said retractable telescopic column partly overlap to form an overlapping section, with a portion of said first band being wound in a helix adjacent to said overlapping section and with said fasteners engaging said overlapping section to releasably link said each two consecutive turns of said second band that form said retractable telescopic column. 
   
   
     16. A linear actuator as defined in  claim 15 , wherein said releasable fasteners are longitudinally spaced-apart teeth protruding from said first band, and said second band comprises longitudinally disposed openings positioned in said each two consecutive turns of said second band that form said retractable telescopic column so as to register in said overlapping section by pairs, with at least some of said pairs of openings being each engaged by a corresponding said tooth. 
   
   
     17. A linear actuator as defined in  claim 16 , wherein said retaining member is a punctual abutment member mounted to said rotor that prevents disengagement of said teeth of said first band from the turn of said second band forming said telescopic column nearest said intermediate portion, with the other turns of said second band forming said telescopic column being securely engaged by said teeth of said first band as long as said turn of said second band forming said telescopic column nearest said intermediate portion remains engaged by said teeth. 
   
   
     18. A linear actuator as defined in  claim 17 , wherein said retaining member is also said guiding member. 
   
   
     19. A linear actuator as defined in  claim 17 , wherein said retaining member is a roller. 
   
   
     20. A linear actuator as defined in  claim 18 , further comprising a second guiding member mounted to said rotor for guiding said second band at said linear actuator intermediate portion. 
   
   
     21. A linear actuator as defined in  claim 20 , wherein said second guiding member is a spring-loaded guide arm pivotally mounted to said rotor. 
   
   
     22. A linear actuator as defined in  claim 14 , further comprising a first anti-rotation member attached to either one of said first and second bands and engaging a second anti-rotation member attached to said frame, wherein said first and second bands are prevented from rotating while they are moved between their extended and retracted positions. 
   
   
     23. A linear actuator as defined in  claim 16 , wherein said teeth are also first anti-rotation members that cooperate with second anti-rotation members provided on said frame in spaced-apart fashion around said central axis, with at least one of said teeth engaging a corresponding space defined between two said second anti-rotation members at all times, whereby said first and second bands are prevented from rotating. 
   
   
     24. A linear actuator having a central axis and comprising:
 a frame including spaced-apart and distinct first and second frame portions; 
 an elongated fastening band comprising a first portion of variable length stacked in a helical configuration and a second portion of variable length also having a helical configuration, said fastening band further comprising longitudinally disposed first releasable fastening means and having a first end located near said first frame portion and a second end attached to said second frame portion; 
 an elongated substantially flat structural band having its turns generally parallel to said central axis and comprising a first portion of variable length stacked in a spiral pattern separately from said fastening band and having a first end located near said first frame portion, a second portion of variable length having a helical configuration and having a second end attached to said second frame portion, and second releasable fastening means that can cooperate with said first fastening means to releasably interlock said structural and fastening bands; 
 a support member carried by said first frame portion and forming a helical pattern about said central axis, with part of said fastening band movably engaging said support member whilst allowing relative rotation of said support member relative to said fastening band; 
 a guiding and retaining member mounted to first frame portion; and 
 drive means to cause relative rotation on one hand of said fastening and horizontal bands and on the other hand of said support member about said central axis; wherein upon relative rotation on one hand of said fastening and structural bands and on the other hand of said support member in a first direction, a retractable telescopic column is formed with the second portions of said fastening and structural bands, by said fastening band being lifted and its turns being spaced through its engagement on said support member, and by each turn of said structural band being guided by said guiding and retaining member into an edgewisely adjacent configuration with respect to the preceding turn of said vertical band to form a substantially continuous cylindrical wall of said column, with said first and second fastening means engaging each other to releasably link each two successive turns of the second portion of said structural band with a corresponding turn of said fastening band, and with said guiding and retaining member retaining said first and second fastening means in their engagement at said each two successive turns of the upper portion of said structural band; and wherein upon rotation of said rotor in the direction opposite said first direction, said retractable telescopic column is retracted. 
 
   
   
     25. A linear actuator as defined in  claim 24 , wherein each said two consecutive turns of said structural band that form said retractable telescopic column partly overlap to form an overlapping section, with a portion of said fastening band being wound in a helix adjacent to said overlapping section and with said first and second fastening means engaging each other at said overlapping section to releasably link said each two consecutive turns of said structural band that form said retractable telescopic column. 
   
   
     26. A linear actuator as defined in  claim 25 , wherein said first fastening means comprise longitudinally spaced-apart teeth protruding from said fastening band, and said second fastening means comprise spaced-apart openings longitudinally disposed along said structural band and positioned in said each two consecutive turns of said structural band that form said retractable telescopic column so as to register in said overlapping section by pairs, with at least some of said pairs of openings being each engaged by a corresponding said tooth. 
   
   
     27. A linear actuator as defined in  claim 26 , wherein said guiding and retaining member is a punctual abutment member mounted to said rotor that prevents disengagement of said teeth of said fastening band from the turn of said structural band forming said telescopic column nearest said structural band first portion, with the other turns of said structural band forming said telescopic column being securely engaged by said teeth of said fastening band as long as said turn of said structural band forming said telescopic column nearest said structural band first portion remains engaged by said teeth. 
   
   
     28. A linear actuator as defined in  claim 27 , wherein said guiding and retaining member is a roller. 
   
   
     29. A linear actuator as defined in  claim 28 , further comprising an additional guiding member mounted to said rotor for guiding said second band towards the telescopic column. 
   
   
     30. A linear actuator as defined in  claim 24 , further comprising a first anti-rotation member attached to either one of said structural and fastening bands and engaging a second anti-rotation member attached to said frame, wherein said structural and fastening bands are prevented from rotating. 
   
   
     31. A linear actuator as defined in  claim 26 , wherein said teeth are also first anti-rotation members that cooperate with second anti-rotation members provided on said frame in spaced-apart fashion around said central axis, with at least one of said teeth engaging a corresponding space defined between two said second anti-rotation members at all times, whereby said structural and fastening bands are prevented from rotating. 
   
   
     32. A linear actuator as defined in  claim 25 , wherein said structural band is preformed in an inclined configuration so that each turn defines a slightly conical shape. 
   
   
     33. A linear actuator as defined in  claim 24 , wherein said drive means includes a power driven rotor rotatably mounted to said first frame portion and carrying said guiding and retaining member and said support member, said linear actuator also comprising a structural band magazine movable relative to said rotor and said frame and carrying said structural band first portion. 
   
   
     34. A linear actuator as defined in  claim 24 , wherein said first frame portion carries said guiding and retaining member and a structural band magazine movable relative to said first frame portion and carrying said structural band first portion, with said second frame portion carrying said drive means that includes a power driven rotor fixedly attached to said first end of said fastening and structural bands and rotatably carried by said second frame portion.